Microstructure and mechanical properties of selective laser melted superalloy inconel 625.

additive manufacturing;selective laser melting;superalloys;inconel 625

Md Ashabul Anam

University:University of Louisville

Department:Industrial Engineering

关键词: additive manufacturing;    selective laser melting;    superalloys;    inconel 625;   

Others  :  https://ir.library.louisville.edu/cgi/viewcontent.cgi?article=4205&context=etd

美国|英语

来源: The Universite of Louisville's Institutional Repository

【 摘 要 】

Selective Laser Melting (SLM), a powder based Additive Manufacturing (AM) process, has gained considerable attention in the aerospace, biomedical and automotive industries due to its many potential benefits, such as, capability of fabricating complex three-dimensional components, shortened design to product time, reduction in process steps, component mass reduction and material flexibility. This process uses metallic powder and is capable of fabricating complex structures with excellent microstructure which make SLM not only an improvement over other manufacturing processes but also innovative material processing technology. Inconel 625, a nickel-based super alloy is widely popular in aerospace, chemical and nuclear industries. This alloy is characterized by having high tensile, creep and rupture strength and is widely used because of its excellent fatigue and good oxidation resistance properties. However, excessive tool wear and low material removal rate make it difficult to manufacture by conventional machining methods at room temperature. Selective laser melting, therefore, becomes a good solution for complex Inconel 625 parts. The formation of constituent phases of this alloy is a function of process parameters such as local temperature, hold time at temperature, local cooling rate and local compositions in the melt-pool. The effect of each process parameter on the resulting microstructure and mechanical properties must be understood in order to properly control the machines and predict the properties of the parts being fabricated. Therefore, the aim of the research work is to investigate the effect of key process variables of SLM systems (the EOS M270 Powder-bed system at The University of Louisville) on the melting response and solidification microstructure of Nickel based super-alloy Inconel 625. The effect of processing parameters on Inconel 625 was investigated on single track deposits and bulk deposits. Multiple combinations of laser power and scan speed were used to fabricate the deposits by selective laser melting (SLM). Surface morphology and dimensions of the single track deposits were characterized using optical and SEM microscopy. To evaluate the geometrical feature of the melt pool, the cross-section of the single track deposits was studied. The result was then utilized to develop a process parameter map which is insightful to identify the optimum parameters that produce high-density parts. Beside laser power and scan speed, scan pattern plays an important role in controlling microstructural features. Therefore, a careful study of scan pattern is important to understand microstructural evolution during SLM. In this study, two types of scanning pattern (Alternating and Rotating) were used